I've bought dozens of batches of commercially-produced biodiesel from the usual local source, Pacific Biodiesel, over the last decade or so, and never have I had this experience until the last batch. The stuff reeked of rotten meat, like a grease-trap. Every other time I've purchased, it's been good-smelling stuff that tends to make me hungry: like popcorn, doughnuts, french-fries, etc. This time, it makes me feel queasy and want to shower.

I called their rep after getting home with the stuff (though not until after I'd managed to slosh it all over myself when a spout let loose from the carrying-container I'd been filling with, which it hit the ground and sent a geyser all over me...yeah, my first major baptism had to be with THIS stuff.) Anyway, he said he couldn't comment on the smell (I think because he doesn't spend much time in their yard) but that they fuel their collection trucks from the same tote that I'd bought mine from, so they'd know if there was a problem. So basically, he shrugged it off, and I was willing to let it go, since it would be a big hassle to "return" the stuff, plus it seemed to be working OK in the one machine I'd filled. I figured I'd bear with it until it was gone.

But I've just recently filled & had some serious problems with the other machine I run with bio. Yes, this could be coincidental (I will be flushing it out and using dino-diesel for a test) but I thought I would ask about that awful smell. Anyone know from experience whether the stench is not so rare, or alternatively, a clear indicator of a "bad batch?"

I don't think I'd have been so regular a customer if I'd run into this before.

I've not noticed any of my home made bio is repulsively stinkey. But I avoid smelling chemicals. Once upon a time I worked in a University organic chemistry research lab. I made some phenyl hydrazine, which was a yellow liquid of a similar viscosity to maybe water. I noticed it had an unusual pleasant odor. I let the PhD candidate see me smell the liquid, and he got upset. He said never smell the chemicals. So as a general principle I avoid smelling chemicals. The actual chemical might not be poison, but a metabolic product of the chemical might be poison. A MD I listened to said, if consumed, methanol metabolizes to formaldehyde, which somehow damages the optic nerve or worse. It can cause blindness or a degree of damage to sight. I believe that (methyl) biodiesel, probably metabolizes in part to formaldehyde somewhere along the metabolic path, so I usually avoid smelling my biodiesel. I have read that microorganisms can grow in biodiesel, especially wet biodiesel. The stinkey odor of the biodiesel in question might be due to an older, wet batch. I expect that the microorganisms may produce (stinkey) butyric acid if given time, and a range of temperature, with wet biodiesel. But that's my guess. I have no reference from scientific literature to back that up with.

Originally posted by WesleyB: A MD I listened to said, if consumed, methanol metabolizes to formaldehyde, which somehow damages the optic nerve or worse. It can cause blindness or a degree of damage to sight.

In a process of toxication, it is metabolized to formic acid (which is present as the formate ion) via formaldehyde in a process initiated by the enzyme alcohol dehydrogenase in the liver.

Methanol is converted to formaldehyde via alcohol dehydrogenase (ADH) and formaldehyde is converted to formic acid (formate) via aldehyde dehydrogenase (ALDH). The conversion to formate via ALDH proceeds completely, with no detectable formaldehyde remaining.Formate is toxic because it inhibits mitochondrial cytochrome c oxidase, causing the symptoms of hypoxia at the cellular level, and also causing metabolic acidosis, among a variety of other metabolic disturbances.

so anyway, as I was asking before the conversation veered off into the chem lab...

Should I conclude that stanky, rank biodiesel is rare? Bad to use?

I'm not talking about your average "chemical smell" - I'm talking about that junior-school memory of the shocking stench that was released when the dentist took your braces off, or when you happened to walk by a crew pumping out a the Arby's grease-trap. NASTY.

Originally posted by DS:I've bought dozens of batches of commercially-produced biodiesel from the usual local source, Pacific Biodiesel Every other time I've purchased, it's been good-smelling stuff that tends to make me hungry: like popcorn, doughnuts, french-fries, etc.

I have never smelled biodiesel that smelled like food. Both in it's liquid state and at the tailpipe. Neither my own or anything commercially made. Even when biodiesel goes rancid, it smells more like turpentine. By chance, are you referring to SVO?

Originally posted by DS:I've bought dozens of batches of commercially-produced biodiesel from the usual local source, Pacific Biodiesel Every other time I've purchased, it's been good-smelling stuff that tends to make me hungry: like popcorn, doughnuts, french-fries, etc.

I have never smelled biodiesel that smelled like food. Both in it's liquid state and at the tailpipe. Neither my own or anything commercially made. Even when biodiesel goes rancid, it smells more like turpentine. By chance, are you referring to SVO?

No, 'pure' biodiesel, from Pacific Biodiesel.

You've never smelled biodiesel that smells like food? Is your source direct from the plant, then? I've never NOT smelled food (or rotten food, in this case) on burnt bio exhaust; the raw stuff less so, but never what I'd describe as foul or bad-smelling until this episode.

Originally posted by DS:Should I conclude that stanky, rank biodiesel is rare? Bad to use? ... the Arby's grease-trap. NASTY.

It's likely more common in a populated tropical area where you live. What did you think happens to the nasty stuff from grease traps? It's increasingly made into biodiesel. Caveat emptor.

If it doesn't smell like clean fresh biodiesel, I don't put it in the tanks of my expensive diesel machines.

Pac Biodiesel doesn't make any secret of their source - they also run a fleet of grease-trap-suckers. They get it coming and going...(and, I'd gripe, don't seem to pass the savings on to us, from what I can tell, since it's priced well above the prevailing price of petro-diesel at any given time.) It's possible their mix of sources has changed recently, but that'd be proprietary info I can only speculate on - I can only say their grease-trap sucking has been going on for years.

But I've all but ruled out bad biodiesel as the cause of rapid demise of one of my engines, by swapping for petrodiesel in a temp tank, so rank stench or not, I don't think it's the cause of my engine woes.

I also have never smelled biodiesel that smells like meat or other food, either good or rotten. Biodiesel made from veg oil usually has a kind of sweet smell and biodiesel made from animal fat does not. But in both cases the smell is minimal, You need to get your nose very close to the biodiesel to smell it.I have smelled biodiesel that smelled rancid the same way oil can smell rancid and it is a stronger smell, bit not a rotten smell.